Comparative analysis of antibiotic resistance and biofilm formation in Enterococcus spp. across One Health domains.

The rise of antibiotic-resistant bacteria is a critical issue across various ecological interfaces, highlighting the need for a One Health approach. Enterococcus spp., known for their ability to acquire and disseminate resistance, serve as an excellent model due to their presence in diverse hosts and environments. This study investigates antimicrobial resistance, biofilm formation capacity, and the efficacy of antibiotics on biofilm biomass reduction in isolates from multiple sources. A total of 197 Enterococcus isolates were used. Antimicrobial resistance was determined using the Kirby-Bauer disc diffusion method, and minimum inhibitory concentrations were tested against vancomycin, tetracycline, and ampicillin. Biofilm formation capacity was assessed, and 10 biofilm-formers were subjected to minimum biofilm inhibitory concentration (MBIC) tests to evaluate biofilm biomass reduction. The results showed high resistance rates to erythromycin (84.5%), ciprofloxacin (59.4%), and tetracycline (44.4%), with moderate resistance to ampicillin (36.2%), chloramphenicol (28%), and vancomycin (24.7%). Biofilm formation was observed in 65% of the isolates, with Enterococcus hirae producing the most biofilm biomass. Vancomycin and ampicillin were more effective in reducing biofilm biomass than tetracycline. Ampicillin-resistant isolates produced more biofilm, suggesting a link between resistance and biofilm formation. This study highlights the complexity of antibiotic-resistant Enterococcus spp. and their biofilms, emphasizing the need for research on One Health.